Photophysical properties of CdSe quantum dot self-assemblies with zinc phthalocyanines and azaphthalocyanines

• Published in: Photochemical & photobiological sciences 2013-05, Vol.12 (5), p.743-75
• Main Authors: Suchánek, Jan, Lang, Kamil, Novakova, Veronika, Zimcik, Petr, Zelinger, Zden k, Kubát, Pavel
• Format: Article
• Language: English
• Subjects: Biochemistry; Biomaterials; Cadmium Compounds - chemistry; Chemistry; Indoles - chemistry; Organometallic Compounds - chemistry; Particle Size; Physical Chemistry; Plant Sciences; Quantum Dots; Quantum Theory; Selenium Compounds - chemistry; Solvents - chemistry; Spectrometry, Fluorescence
• ISSN: 1474-905X; 1474-9092
• DOI: 10.1039/c2pp25348h

The formation of self-assemblies between CdSe quantum dots (QDs) and Zn phthalocyanines (Pc) and azaphthalocyanines (AzaPc) bearing alkylsulfanyl substituents and the photophysical properties of these assemblies were studied using both steady-state and time-resolved luminescence/absorption spectroscopy. The formation of the self-assemblies was accompanied by a blue shift of the Q band of the dyes and by a quenching of the CdSe QDs luminescence. The largest spectral shift of the Q-band was approximately 7 nm and was observed for pentan-3-ylsulfanyl-functionalised phthalocyanine ( 3 ). Assuming a 1 : 1 stoichiometry, the calculated binding constant was 4 × 10 4 M −1 . Pc substituted with the bulky tert -butylsulfanyl groups ( 1 ) exhibited a smaller shift of the Q band. The quenching of the CdSe QDs luminescence by 1 was more effective than that observed for 3 . The results indicated that the luminescence quenching may be due to a photoinduced charge transfer between 1 or 3 and the CdSe QDs. In contrast, the AzaPc ( 2 ) with the same substituents as 1 had little effect on the QDs luminescence. For all cases, we found an inefficient resonance energy transfer between the attached dyes and the CdSe QD. The formation of the self-assemblies had negligible effects on the photogeneration of the singlet oxygen, O 2 ( 1 Δ g ), that was fully controlled only by the absorption of the light by the macrocycles. The formation and the photophysical properties of self-assemblies between CdSe quantum dots and Zn phthalocyanines and azaphthalocyanines bearing alkylsulfanyl substituents were studied using luminescence/absorption spectroscopy.